Archive for September, 2012

When water flows over stones, it smooths them out and carries them in its path. Even when the steam has long since dried up, the gravel it leaves behind provides distinct evidence of the water’s former presence. And now the Curiosity rover has found tell-tale gravel embedded in the Martian bedrock, small stones rounded by water and too large for wind to have transported—rocky proof of water’s presence on the Red Planet. Although previousphotossuggested that water once flowed on Mars, the rocks in outcrops like the one pictured here, dubbed “Hottah” after Canada’s Hottah Lake, are the most definitive evidence of water on Mars that we have ever found.

Hummingbirds are incredible flyers, with the ruby-throated hummingbird beating its wings 80 times every second, an ability that inspired this blog’s name. These tiny birds can fly forwards, hover, and are the only known birds to fly backwards as well. But although zooming backwards is the rarest of the hummingbird’s flying tricks, a paper in the Journal of Experimental Biology reveals that it takes no more energy than moving forwards.

It goes without saying that the drugs you take for a headache, or high blood pressure, or even depression should work better than a Tic-Tac. That’s what drug trials are for: researchers give a group of subjects either the drug under investigation or a placebo to check that the medicine is significantly more effective than a sugar pill. Plus, the trials can reveal any potentially harmful side effects. In theory, this is a great way to weed out useless or actively harmful drugs. But it fails when drug manufacturers cherry-pick their data, publishing papers on the positive trials and sweeping the unsuccessful ones under the rug. And this behavior is completely legal.

Science writer and medical doctor Ben Goldacre wrote a book, with a long excerpt published at the Guardian, about how this process leads to approval for drugs that don’t actually work. And as he explains, when widely used drugs—such as the diabetes medication rosiglitazone—have harmful side effects, they sometimes remain in common use.

Some women always have men on the brain. And some women literally have men in their brains. A new study in PloS ONE found that quite a few female brains contain male DNA. This genetic material presumably passes into a mother while she is pregnant with a male fetus. Although we already knew that fetal cells can enter a mother’s body, until now, it was unknown whether the cells could pass into the brain as well, because the blood brain barrier normally blocks large molecules and foreign substances from entering the brain.

To explore the possibility of brain microchimerism—the presence of genetically distinct cells in a host’s body—researchers examined autopsy specimens from 59 deceased female subjects, who either had no neurological disease or had suffered from Alzheimer’s. The scientists found that 63 percent of the brains contained male cells distributed throughout the organ, and that this microchimerism did not fade away over time: the brain of one 94-year-old woman still contained male cells. And interestingly, the brains of subjects with Alzheimer’s disease were less likely to contain male DNA, and when they did, they generally had less of it than the healthy brains did.

We humans aren’t the most logical creatures. Take information processing: if we were perfect reasoners, we would absorb all the new facts we learn and use them to modify our view of the world. But while we do something like this with good news, bad news tends to go in one ear and out the other. While this good news / bad news effect gives you a more positive outlook on life, it can make you blindly optimistic, unprepared for the real consequences of medical problems or natural disasters.

Fans of marine trivia may already know that a starfish is a messy eater. Instead of putting prey in their stomachs, many starfish species put their stomachs into their prey, throwing up this organ inside-out and letting its acidic juices break down the food into nutrient soup. Then the starfish slurps up its meal, sucks its stomach back in, and shuffles on its merry way.

Bacteria invisible to the naked eye find their way to many of the external surfaces of our bodies, including the naked eye. But the eye isn’t defenseless against this onslaught of microbes—researchers have found that it has special weapons for fighting back.

This fight happens at the surface of the cornea, the eye’s clear outer layer. New research published in the Journal of Clinical Investigation has found that keratin—a type of protein that gives structure to the cornea and other tissues like skin, teeth, hair, and mucous membranes—protects against bacteria. If the eye is like a fishbowl, it’s made of shards used for self-defense. Researchers say the new finding may lead to the creation of new kinds of antibiotics.

Coronaviruses derive their name from the corona visible in
images such as this 1975 transmission electron micrograph
of infectious bronchitis viruses

When a 49-year-old Qatari man fell ill in England this month, doctors realized that his respiratory problems and kidney failure were due to a previously unknown virus. Earlier this year, a nearly identical virus, 99.5 percent genetically identical to be exact, killed a middle-aged Saudi man. While a new disease is always cause for caution, there have been only two confirmed cases thus far. So what’s the worry? The problem is that this new virus belongs to a family called coronaviruses, a family that includes the common cold…and the deadly and fast-spreading Severe Acute Respiratory Syndrome, or SARS.

Unlike pesticide-laden conventional food, organic produce is more natural, healthier, and better for you…right? Organic food does contain less synthetic pesticides. But the natural pesticides that replace them can also have harmful effects. For example, the organic pesticide copper sulfate is more toxic than some synthetic pesticides, and it can cause genetic mutations, cancer, liver disease, and anemia. No matter what you choose to eat, both conventional and organic produce can expose you to low levels of pesticides. Before you forswear all greens, however, bear in mind that low pesticide levels aren’t the worst thing in the world.

At her Science Sushi blog on Scientific American’s network, Christie Wilcox explains that a little bit of pesticide exposure can actually be good for you.

Plant researchers who want to study the roots of growing plants have a problem: Those roots are obscured by the soil in which the plant grows. But no more hiding. Now researchers have designed a transparent soil that lets them look at not only roots but also the microbes, good and bad, that colonize them.